Since the 2025.1.0 release, dask_expr is actually part of the dask package.

https://archlinux.org/todo/drop-python-pytest-cov-dependency-if-unneeded/

loqs authored 11 months ago and Jelle van der Waa committed 10 months ago

https://github.com/dask/dask/blob/2023.8.0/LICENSE.txt

Switch to PEP517.
Ignore tests that try to use a distributed setup.

Upstream expect it to be available.
Also enable more tests by adding deps.